A thermal control system is required to maintain the operability of electronic components disposed within an enclosure located in a hostile environment. It is recommended that the thermal control system maintain a maximum operating temperature for electronic components in the range of 70.degree.-80.degree. C. independent of the environment outside the chassis. The maximum operating temperature range of 70.degree.-80.degree. C. is variable because the electronic components typically have different specifications and grades. Hostile environments having extreme operating conditions such as high or low temperatures may also include elements such as salt, fog, dust, sand, humidity or other contaminants. Also, extreme operating conditions having low temperatures near -40.degree. C. make it difficult for commercial electronic components to operate.
Traditional thermal control systems designed to operate at the chassis level include technologies such as free or forced air convection, conduction, liquid cooling, and immersion cooling. The free or forced air convection approach of directly cooling electronic components is problematic, because the components are often introduced to dust, salt, moisture or other damaging elements. Furthermore, the convection approach alone is not an adequate way of heating the electronic components operating in temperatures ranging from -40.degree. through 0.degree. C.
The conductive approach uses heat sinks, cold plates or thermal planes to absorb and transport heat generated by the electronic components. The heat sinks, cold plates and thermal planes must physically contact the electronic components, therefore, limiting design flexibility and increasing the weight of the enclosure. The increased weight further reduces the enclosure operational limits by narrowing the vibrational limits of electronic components. Also, the conductive approach is undesirable due to the cost associated with cold plates and thermal planes. An additional disadvantage associated with conductive cooling is that the additional thermal mass limits the ability to heat the electronic components to acceptable limits when the electronic components are operating at low temperatures.
The efficiency of the conductive approach using the cold plates may be enhanced by adding thermal bags or thermally conductive foams to improve a conductive path between the cold plate and electronic components. However, the additional cost and weight are still disadvantages associated with the thermal bags or thermally conductive foams.
Generally the liquid cooling and immersion cooling approaches are more effective than the convection or conduction approaches. However, the liquid cooling approach requires complex fluid and tubing distribution schemes that are very expensive, and the immersion cooling approach has disadvantages attributable to the added weight and nucleate boiling hysteresis associated with immersing the electronic components in the fluid.
U.S. Pat. No. 5,220,804, issued to Tilton et al., discloses an array of perpendicular atomizers that spray cooling liquid onto electronic components. The atomizers include nozzles that individually direct the cooling liquid to a corresponding electronic component.
U.S. Pat. No. 5,311,931, issued to Lee, discloses a method of generating a spray mist that forms an ultra-thin coolant film and intentionally produces a vortex within a cavity associated with electronic components.
U.S. Pat. No. 4,399,484, issued to Mayer, discloses a jet cooling system that has direct impingement fluid flow perpendicular to a surface of a printed circuit board. The printed circuit board has passages for the cooling fluid.
U.S. Pat. No. 5,349,831, issued to Daikoku et al., discloses a device that discharges cooling fluid having a perpendicular flow to electronic components.
U.S. Pat. No. 5,021,924 discloses a semiconductor cooling device having a plurality of nozzles associated with each electronic component. The nozzles are located at substantially the same level with the surface of the electronic component.
Accordingly, there is a need for an enclosure to provide an improved environment for electronic components that are located within the enclosure. Also there is a need for an enclosure having a significantly increased cooling and/or heating capacity. These and other needs are addressed by the spray cooled enclosure of the present invention.